tag:theconversation.com,2011:/global/topics/natural-pesticides-73288/articles
Natural pesticides – The Conversation
2024-01-29T13:35:17Z
tag:theconversation.com,2011:article/204673
2024-01-29T13:35:17Z
2024-01-29T13:35:17Z
That sharp, green smell of freshly cut grass? It’s a plant’s cry for help – and it may work as a less toxic pesticide for farmers
<figure><img src="https://images.theconversation.com/files/570226/original/file-20240118-15-wd2xly.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4928%2C3260&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Green leaf volatiles are a plant's rapid response to threats.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Green_leaf_vein.jpg">Star61/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Have you ever wondered about that sharp, green note that hits your nose when you mow the lawn or cut flower stems? Those are <a href="https://doi.org/10.1093/pcp/pcac117">green leaf volatiles, or GLVs</a>: easily evaporated oils that plants use to communicate with other plants and defend themselves against herbivores or pathogens like bacteria or fungi.</p>
<p>Almost every green plant can quickly <a href="https://doi.org/10.1093/pcp/pcac117">synthesize and release GLVs</a> when attacked, both directly warding off attackers as well as indirectly attracting predators of herbivores like insects and priming the plant’s other defense mechanisms. Researchers know that GLVs play an important role in protecting plants, but how they work remains unclear.</p>
<p>I am a <a href="https://sc.edu/study/colleges_schools/chemistry_and_biochemistry/our_people/students_researchers_emeritus/tan-arsuwongkul_sasimonthakan.php">biochemistry researcher</a>, and through a collaboration between the <a href="https://qianwanggroup.com/">Wang Lab</a> and <a href="http://research.cas.sc.edu/stratmann/">Stratmann Lab</a> of the University of South Carolina, my colleagues and I study how plant cells deploy green leaf volatiles. In our <a href="http://doi.org/10.1111/pce.14795">recently published research</a>, we identified the potential signaling pathways GLVs use to induce defense responses in tomato cells. Our ultimate goal is to figure out ways to use GLVs to control agricultural pests for cleaner farming.</p>
<h2>Defense systems in plants</h2>
<p>Plants employ many defense systems to protect themselves. The <a href="https://doi.org/10.3389/fpls.2019.00646">first line of defense</a> involves detecting microbial invaders and the presence of damage using <a href="https://doi.org/10.1146/annurev-phyto-082718-100146">damage-associated molecular patterns, or DAMPs</a>, which are molecules released by damaged or dying cells.</p>
<p>When a cell identifies a DAMP, it triggers an immune response and promotes repair mechanisms. It also leads to <a href="https://doi.org/10.3389/fpls.2021.795353">changes in calcium ion concentration</a>, further activating immune-related genes and proteins. DAMPs also <a href="https://doi.org/10.1111/jipb.13215">turn on proteins</a> common in many stress-signaling pathways that activate other defense responses.</p>
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<figcaption><span class="caption">Plants have several means of defense.</span></figcaption>
</figure>
<p>Many studies have shown that the <a href="https://doi.org/10.3389/fpls.2014.00578">effects of</a> <a href="https://doi.org/10.1111/nph.12977">GLVs are</a> <a href="https://doi.org/10.3389/fpls.2020.583275">similar to</a> <a href="https://doi.org/10.1584/jpestics.d18-020">DAMPs</a>. Therefore, my team and I wanted to prove whether GLVs may also act as DAMPs.</p>
<p>To do this, we studied which proteins are turned on or off in tomato cells. Chemically changing the structure of a protein through a process called <a href="https://doi.org/10.1038/ncb0502-e127">phosphorylation</a> turns it on or off. Protein phosphorylation plays a central role in regulating a great number of cellular processes and involves many signal transmission pathways. <a href="https://doi.org/10.1186%2Fgb-2005-6-9-230">Studying the phosphoproteome</a>, or all the proteins that are phosphorylated in one system, of tomato cells could help us compare the signaling pathways of GLVs and DAMPs.</p>
<p>We found that many of the proteins involved in green leaf volatile signaling pathways were involved in regulating stress. These included many components of DAMP signaling pathways, supporting our hypothesis that GLVs function like DAMPs in activating defense responses.</p>
<h2>Using GLVs in agriculture</h2>
<p>Agriculture often places significant pressure on natural resources and the environment. For example, the use of conventional pesticides can lead to <a href="https://theconversation.com/farmers-and-cropdusting-pilots-on-the-great-plains-worried-about-pesticide-risks-before-silent-spring-91976">environmental degradation and pest resistance</a>. </p>
<p><a href="https://doi.org/10.3389/fsufs.2021.619058">Biopesticides</a> are rising in popularity as a less toxic alternative. These are naturally occurring organisms or compounds that suppress the growth and spread of pests. For example, <a href="https://doi.org/10.1016/j.jafr.2021.100127">volatile organic compounds</a> from plants are a type of biopesticide that have been proven to allow for reduced use of synthetic insecticides to manage pests in stored food grains.</p>
<p>Therefore, GLVs may also be effective biopesticides in farming. One study has shown that GLVs can attract a plant pest, the <em>Apion miniatum</em> beetle, <a href="https://doi.org/10.3390/app13042253">to feed on</a> an invasive and difficult to control weed, <em>Rumex confertus</em>. In addition, field studies on wild tobacco plants found that releasing GLVs can attract enemies of herbivores. The presence of these herbivore competitors can not only control insect pests but also <a href="http://dx.doi.org/10.7554/elife.00007">increase the production of infested plants</a>.</p>
<p>With further research, we believe GLVs have the potential to naturally control pests and support sustainable agriculture.</p><img src="https://counter.theconversation.com/content/204673/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sasimonthakan Tanarsuwongkul does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Green plants produce a specific gas when under attack to both directly ward off herbivores and pathogens and indirectly lure in herbivore predators.
Sasimonthakan Tanarsuwongkul, Ph.D. Candidate in Biochemistry, University of South Carolina
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/207050
2023-07-27T14:26:27Z
2023-07-27T14:26:27Z
Pesticides are harming Nigeria: it’s time to update the law
<figure><img src="https://images.theconversation.com/files/537783/original/file-20230717-207908-ow9gwb.jpg?ixlib=rb-1.1.0&rect=40%2C0%2C4464%2C2926&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Without strict regulation, farmers misuse pesticides. Kola Sulaimon/AFP/</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/godwin-teremun-a-rice-farmer-fumigates-his-farm-after-news-photo/1234769539?adppopup=true">Getty Images</a></span></figcaption></figure><p>The European Union has banned the use of several pesticides, and heavily restricted others. This is because of their potential health effects or environmental contamination, or because there’s not enough data to be sure that they aren’t harmful. Over <a href="https://ng.boell.org/sites/default/files/2023-03/pesticideatlas2022_nigeria_compressed.pdf#page=16">50%</a> of these pesticides are still registered in Nigeria, however. </p>
<p>Nigeria’s use of such pesticides is the reason some markets, including the EU and the US, <a href="https://von.gov.ng/nigerian-government-strategizes-to-lift-eu-ban-on-agricultural-export/">reject</a> the country’s agricultural products. Yet some countries with strict regulations at home still export the banned pesticides to countries like Nigeria. </p>
<p>As a <a href="https://www.uottawa.ca/faculty-law/common-law/research/postdoctoral-studies/sparking-conversation/meet-jane-ezirigwe">researcher</a> in the field of food and agricultural law, international trade and natural resource development, I’ve <a href="https://www.jutajournals.co.za/legal-and-policy-measures-to-curtail-harmful-use-of-agrichemicals-in-nigeria/">explored</a> the laws and regulations that govern the use of pesticides. My research highlights the gaps that undermine export opportunities.</p>
<p>I identified four major factors that make Nigeria’s pesticide regulations ineffective. They are: outdated laws; overlapping regulatory functions; resource limitations; and the influence of multinationals.</p>
<p>Good pesticide regulation should do three main things: protect people and the planet, support effective pest control, and provide redress when harm occurs. </p>
<p>Better regulation will make Nigeria’s agricultural products safer for local consumption and export.</p>
<h2>Limiting factors</h2>
<p><strong>Outdated laws:</strong> Nigeria’s laws are <a href="https://www.jutajournals.co.za/legal-and-policy-measures-to-curtail-harmful-use-of-agrichemicals-in-nigeria/">outdated</a>. The laws that regulate pesticides do not stop Nigerians from importing banned chemical products. </p>
<p>More than half of the products approved by the National Agency for Food and Drug Administration and Control, the principal agency for pesticides control, contain harmful active ingredients banned by the European Union. </p>
<p>There are no provisions to hold manufacturers accountable for the negative impact of hazardous pesticides. No law requires people to use personal protective equipment when applying pesticides. And there’s no legal duty to monitor residue in food. </p>
<p><strong>Overlapping regulatory functions:</strong> The agencies regulating pesticide use in Nigeria don’t work together. Some of their functions overlap and other functions are neglected. A national pesticide policy was <a href="https://punchng.com/naqs-to-unveil-nigerias-first-national-pesticide-policy/">announced</a> in March 2019 to help coordinate what they do. But it hasn’t been put into practice. </p>
<p>The regulators and civil society organisations that are supposed to enforce rules and protect consumers don’t collaborate either. The regulatory agencies could get valuable insights and feedback from farmers’ associations, for example. This lack of cooperation makes it harder to develop and use robust regulations.</p>
<p><strong>Resources and financial limitations:</strong> Agencies of government are unable to function effectively because of limited financial and human resources. For example, they may not have adequate machinery and laboratories to test products. </p>
<p><strong>Influence of multinationals:</strong> Big multinational companies have a lot of power. For instance, the proposed bill to establish a pesticides council reserves two seats for an internationally affiliated association, CropLife Nigeria.</p>
<p>CropLife comprises private companies like Syngenta and Bayer that manufacture highly hazardous pesticides. Council members can make decisions and provide strategic direction. With CropLife as a council member, the regulated becomes part of the regulator. Instead, the council should consist of neutral and independent organisations from the scientific and academic communities. </p>
<h2>Why effective regulation matters</h2>
<p>In 2020, over 270 people <a href="https://www.dw.com/embed/480/av-59457934">died</a> from pesticide poisoning of a community river in Benue State. </p>
<p>A recent <a href="https://ng.boell.org/sites/default/files/2022-12/swofon-survey-final-draft.pdf">survey</a> by the Alliance for Action on Pesticide in Nigeria and Small-scale Women Farmers Organisation in Nigeria showed that <a href="https://ng.boell.org/sites/default/files/2022-12/swofon-survey-final-draft.pdf#page=3">80%</a> of the pesticides used most frequently by small-scale farmers were hazardous. Seventy-five percent of the women farmers in the survey reported symptoms from using pesticides. They include respiratory and eye problems, dizziness, vomiting and skin rashes. </p>
<p>Without strict regulation and enforcement, farmers might misuse or overuse pesticides in farms and storerooms. This would lead to <a href="https://www.ajol.info/index.php/ijs/article/view/156080/145706">environmental contamination and health hazards</a> for farmers and consumers. </p>
<p>The average Nigerian consumer is unaware of the amount of pesticides in the food they consume. But Nigeria’s food exports are tested regularly, and pesticide residues far exceed maximum limits on some crops. </p>
<p>These regulatory lapses have blocked export opportunities. Since 2015, the European Union has <a href="https://von.gov.ng/nigerian-government-strategizes-to-lift-eu-ban-on-agricultural-export/#:%7E:text=(The%20EU%20in%20June%2C%202015,be%20dangerous%20to%20human%20health).">banned</a> agricultural products from Nigeria that contain pesticide residues. These <a href="https://www.premiumtimesng.com/news/more-news/233055-eu-rejected-24-nigerian-products-in-2016-nafdac.html?tztc=1">include</a> groundnut, palm oil, sesame seed and beans.</p>
<p>Weak regulations also make Nigeria vulnerable to becoming a <a href="https://ng.boell.org/sites/default/files/2021-02/Time%20for%20a%20Detox%20in%20Agriculture_2021.pdf">dumping ground</a> for internationally banned and counterfeit pesticides. </p>
<h2>What needs to be done</h2>
<p>Nigeria can learn from <a href="https://ipen.org/news/tunisia-should-move-ban-33-dangerous-pesticides">Tunisia</a>, <a href="https://beyondpesticides.org/dailynewsblog/2020/07/mexico-announces-glyphosate-roundup-phaseout">Mexico</a> and <a href="https://eu.boell.org/en/PesticideAtlas-imports-exports">Palestine</a>. They have passed laws that prohibit pesticides that are banned in the countries that make or export them. </p>
<p>The legal community should engage in public interest litigation to hold manufacturing companies accountable for harm caused by pesticides. </p>
<p>The government should do more to inform farmers, pest control operators and extension officers. A community-based, hands-on safety programme will be more effective than formal training.</p>
<p>Food consumers also need to know about pesticide residues in food. The media should inform the public.</p>
<p>Lastly, <a href="https://www.vanguardngr.com/2023/04/high-applications-of-pesticides-puts-nigerian-consumers-at-risk-report/">alternatives to toxic pesticides exist</a> and should be promoted as good ways to manage pests. </p>
<p>These steps will give Nigerian agricultural products a better chance of acceptance in the international market. </p>
<p><em>Ofoegbu Donald Ikenna, senior programme manager, Sustainable Nigeria programme, Heinrich Boell Stiftung (hbs) Nigeria office, contributed to this article.</em></p><img src="https://counter.theconversation.com/content/207050/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jane Ezirigwe does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Nigeria’s agricultural products are banned by many western countries because of toxic pesticides. Good regulation can address the problem.
Jane Ezirigwe, Postdoctoral Fellow, L’Université d’Ottawa/University of Ottawa
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/188939
2022-11-15T13:22:40Z
2022-11-15T13:22:40Z
Ants – with their wise farming practices and efficient navigation techniques – could inspire solutions for some human problems
<figure><img src="https://images.theconversation.com/files/494699/original/file-20221110-21-p2hi2g.jpg?ixlib=rb-1.1.0&rect=10%2C0%2C2235%2C1329&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Leafcutter ants cultivate fungus gardens that feed sprawling colonies.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/three-leafcutter-ants-carrying-leaves-close-up-royalty-free-image/200187319-004">Tim Flach/Stone via Getty Images</a></span></figcaption></figure><p>King Solomon may have gained some of his famed wisdom from an unlikely source – ants.</p>
<p>According to a <a href="https://www.jewishencyclopedia.com/articles/13842-solomon#anchor14">Jewish legend</a>, Solomon conversed with a clever ant queen that confronted his pride, making quite an impression on the Israelite king. In the biblical book of <a href="https://www.biblegateway.com/passage/?search=Proverbs%206%3A6-8&version=KJV">Proverbs (6:6-8)</a>, Solomon shares this advice with his son: “Look to the ant, thou sluggard, consider her ways and be wise. Which having no guide, overseer, or ruler, provideth her meat in the summer, and gathereth her food in the harvest.”</p>
<p>While I can’t claim any familial connection to King Solomon, despite sharing his name, I’ve long admired the wisdom of ants and have spent over 20 years <a href="https://scholar.google.com/citations?user=bnXkcNUAAAAJ&hl=en&oi=sra">studying their ecology, evolution and behaviors</a>. While the notion that ants may offer lessons for humans has certainly been around for a while, there may be new wisdom to gain from what scientists have learned about their biology.</p>
<figure>
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<figcaption><span class="caption">Ants have evolved highly complex social organizations.</span></figcaption>
</figure>
<h2>Lessons from ant agriculture</h2>
<p>As a researcher, I’m especially intrigued by <a href="https://doi.org/10.1093/isd/ixab029">fungus-growing ants</a>, a group of 248 species that cultivate fungi as their main source of food. They include 79 species of <a href="https://wwnorton.com/books/9780393338683">leafcutter ants</a>, which grow their fungal gardens with freshly cut leaves they carry into their enormous underground nests. I’ve excavated hundreds of leafcutter ant nests from Texas to Argentina as part of the scientific effort to understand how these ants coevolved with their fungal crops.</p>
<p>Much like human farmers, each species of fungus-growing ant is very particular about the type of crops they cultivate. Most varieties descend from a type of fungus that the ancestors of fungus-growing ants began growing <a href="https://doi.org/10.1093/isd/ixab029">some 55 million to 65 million years ago</a>. Some of these fungi became domesticated and are now unable to survive on their own without their insect farmers, much like some human crops such as maize.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/-XuPtW8lBCM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Ants started farming tens of millions of years before humans.</span></figcaption>
</figure>
<p>Ant farmers face many of the same challenges human farmers do, including the threat of pests. A parasite called <a href="https://doi.org/10.1186/s43008-021-00078-8"><em>Escovopsis</em></a> can devastate ant gardens, causing the ants to starve. Likewise in human agriculture, pest outbreaks have contributed to disasters like the <a href="https://evolution.berkeley.edu/the-relevance-of-evolution/agriculture/monoculture-and-the-irish-potato-famine-cases-of-missing-genetic-variation/">Irish Potato Famine</a>, the 1970 <a href="https://doi.org/10.1126/science.171.3976.1113">corn blight</a> and the <a href="https://theconversation.com/with-the-familiar-cavendish-banana-in-danger-can-science-help-it-survive-64206">current threat to bananas</a>.</p>
<p>Since the 1950s, human agriculture has become industrialized and relies on <a href="https://www.birmingham.ac.uk/research/quest/preserving-and-creating-culture/a-global-history-of-monoculture.aspx">monoculture</a>, or growing large amounts of the same variety of crop in a single place. Yet monoculture makes crops more vulnerable to pests because it is easier to destroy an entire field of genetically identical plants than a more diverse one.</p>
<p>Industrial agriculture has looked to chemical pesticides as a partial solution, turning agricultural pest management into a <a href="https://www.alliedmarketresearch.com/pest-control-market">billion-dollar industry</a>. The trouble with this approach is that pests can <a href="https://islandpress.org/books/chasing-red-queen">evolve new ways to get around pesticides</a> faster than researchers can develop more effective chemicals. It’s an arms race – and the pests have the upper hand.</p>
<p>Ants also <a href="https://mitpress.mit.edu/9780262543200/the-convergent-evolution-of-agriculture-in-humans-and-insects/">grow their crops in monoculture</a> and at a similar scale – after all, a leafcutter ant nest can be home to <a href="https://wwnorton.com/books/9780393338683">5 million ants</a>, all of which feed on the fungi in their underground gardens. They, too, use a pesticide to control <em>Escovopsis</em> and other pests. </p>
<p>Yet, their approach to pesticide use differs from humans’ in one important way. Ant pesticides are <a href="https://doi.org/10.1021/acscentsci.0c00978">produced by bacteria</a> they allow to grow in their nests, and in some cases even on their bodies. Keeping bacteria as a living culture allows the microbes to <a href="https://doi.org/10.1128/AEM.00178-21">adapt in real time</a> to evolutionary changes in the pests. In the arms race between pests and farmers, farming ants have discovered that live bacteria can serve as pharmaceutical factories that can keep up with ever-changing pests.</p>
<p>Whereas recent developments in agricultural pest management have focused on <a href="https://entomology.ca.uky.edu/ef130">genetically engineering</a> <a href="https://www.nature.com/scitable/knowledge/library/use-and-impact-of-bt-maize-46975413/">crop plants</a> to produce their own pesticides, the lesson from 55 million years of ant agriculture is to <a href="https://doi.org/10.3389/fsoil.2022.833181">leverage living microorganisms</a> to make <a href="https://doi.org/10.1007/978-981-16-4843-4_13">useful products</a>. Researchers are currently experimenting with <a href="https://link.springer.com/book/10.1007/978-981-10-0707-1">applying live bacteria to crop plants</a> to determine if they are effective at producing pesticides that can evolve in real time along with pests.</p>
<h2>Improving transportation</h2>
<p>Ants can also offer practical lessons in the realm of transportation.</p>
<p>Ants are notoriously good at quickly locating food, whether it’s a dead insect on a forest floor or some crumbs in your kitchen. They do this by leaving a <a href="https://doi.org/10.1111/j.1365-3032.2008.00658.x">trail of pheromones</a> – chemicals with a distinctive smell ants use to guide their nest mates to food. The shortest route to a destination will accumulate the most pheromone because more ants will have traveled back and forth along it in a given amount of time.</p>
<p>In the 1990s, computer scientists developed a <a href="https://www.sciencedirect.com/topics/engineering/ant-colony-optimization">class of algorithms</a> modeled after ant behavior that are very effective at finding the shortest path between two or more locations. Like with real ants, the shortest route to a destination will accumulate the most virtual pheromone because more virtual ants will have traveled along it in a given amount of time. Engineers have used this simple but effective approach to <a href="https://doi.org/10.1016/j.mcm.2010.04.021">design telecommunication networks</a> and <a href="https://doi.org/10.1007%2F978-3-030-50146-4_25">map delivery routes</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/494755/original/file-20221110-3879-61v327.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Leafcutter ants crowding a patch of dirt" src="https://images.theconversation.com/files/494755/original/file-20221110-3879-61v327.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/494755/original/file-20221110-3879-61v327.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/494755/original/file-20221110-3879-61v327.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/494755/original/file-20221110-3879-61v327.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/494755/original/file-20221110-3879-61v327.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/494755/original/file-20221110-3879-61v327.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/494755/original/file-20221110-3879-61v327.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Thousands of ants can travel along the same path without causing traffic jams.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/close-up-of-plant-growing-on-field-royalty-free-image/764924521">Esteban Castao Solano/EyeEm via Getty Images</a></span>
</figcaption>
</figure>
<p>Not only are ants good at finding the shortest route from their nests to a source of food, thousands of ants are capable of traveling along these routes without causing traffic jams. I recently began collaborating with physicist <a href="https://scholar.google.com/citations?user=reX35vUAAAAJ&hl=es">Oscar Andrey Herrera-Sancho</a> to study how leafcutter ants maintain such a steady flow along their foraging paths without the slowdowns typical of crowded human sidewalks and highways.</p>
<p>We are <a href="http://solomon.rice.edu/2019/01/11/field-research-in-costa-rica/">using cameras to track</a> how each individual ant responds to artificial obstacles placed on their <a href="https://www.alexanderwild.com/Ants/Making-a-Living/The-Farming-Ants-Leafcutters/i-rWjNDhM/A">foraging trails</a>. Our hope is that by getting a better understanding of the rules ants use to respond to both obstacles and the movement of other ants, we can develop algorithms that can eventually help program self-driving cars that never get stuck in traffic.</p>
<h2>Look to the ant</h2>
<p>To be fair, there are plenty of ways ants are far from perfect role models. After all, some ant species are known for <a href="https://www.hup.harvard.edu/catalog.php?isbn=9780674241558">indiscriminate killing</a>, and others for <a href="https://theconversation.com/slave-ants-and-their-masters-are-locked-in-a-deadly-relationship-36737">enslaving babies</a>. </p>
<p>But the fact is that ants <a href="https://www.basicbooks.com/titles/mark-w-moffett/the-human-swarm/9781541617292/">remind us of ourselves</a> – or the way we might like to imagine ourselves – in many ways. They live in complex societies with <a href="https://doi.org/10.1007/s00265-015-2045-3">division of labor</a>. They <a href="https://www.simonandschuster.com/books/Ants-At-Work/Deborah-Gordon/9781451665703">cooperate to raise their young</a>. And they accomplish <a href="https://press.princeton.edu/books/hardcover/9780691179315/ant-architecture">remarkable engineering feats</a> – like building structures with air funnels that can house millions – all without blueprints or a leader. Did I mention their societies are <a href="https://www.press.jhu.edu/books/title/10551/secret-lives-ants">run entirely by females</a>?</p>
<p>There is still a lot to learn about ants. For example, researchers still don’t fully understand <a href="https://doi.org/10.1016/j.tree.2020.11.010">how an ant larva develops</a> into either a queen – a female with wings that can live for 20 years and lay millions of eggs – or a worker – a wingless, often sterile female that lives for less than a year and performs all the other jobs in the colony. What’s more, scientists are constantly discovering new species – <a href="https://www.antwiki.org/wiki/Taxa_Described_in_2021">167 new ant species</a> were described in 2021 alone, bringing the total to more than 15,980. </p>
<p>By considering ants and their many fascinating ways, there’s plenty of wisdom to be gained.</p><img src="https://counter.theconversation.com/content/188939/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Scott Solomon receives funding from the National Science Foundation and the Big Thicket Association. </span></em></p>
Over hundreds of million years of evolution, ants have come up with some pretty smart solutions to problems of agriculture, navigation and architecture. People could learn a thing or two.
Scott Solomon, Associate Teaching Professor of Ecology and Evolutionary Biology, Rice University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/134976
2020-04-27T12:09:14Z
2020-04-27T12:09:14Z
A global mask shortage may leave farmers and farm workers exposed to toxic pesticides
<figure><img src="https://images.theconversation.com/files/330437/original/file-20200424-163088-sivov4.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5092%2C3290&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Applying insecticide to a cotton field in Colfax, La.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/colfax-louisiana-cotton-fields-rows-of-cotton-farming-with-news-photo/629539249?adppopup=true">Education Images/Getty Images</a></span></figcaption></figure><p>As the COVID-19 pandemic spreads around the world, vital N95 masks and other personal protective equipment have been hard to come by, even for those who need them most.</p>
<p>The World Health Organization estimates that the crisis has driven demand for this equipment, known as PPE, <a href="https://apnews.com/6d9382c1e8ee36f9ed1a4dfe7815ceb1">100 times higher than normal</a>. Even with dramatic increases in production, manufacturers have said they’ll likely be <a href="https://www.3m.com/3M/en_US/worker-health-safety-us/covid19/">unable to meet demand</a> for the foreseeable future.</p>
<p>And the WHO has warned that the severe shortage is <a href="https://www.who.int/news-room/detail/03-03-2020-shortage-of-personal-protective-equipment-endangering-health-workers-worldwide">putting the lives of health care workers at risk</a>. </p>
<p>But it’s not just health care workers and other care providers who need PPE – especially those N95 masks, technically known as respirators. These devices are also vital to the safety of workers in a host of other industries, from building trades to agriculture. </p>
<p>As an entomologist who studies and teaches about <a href="https://scholar.google.com/citations?user=x3MmknQAAAAJ&hl=en">pesticide risk reduction</a>, I am particularly concerned about what the shortage may mean for farmworkers, whom the Department of Homeland Security <a href="https://www.cisa.gov/publication/guidance-essential-critical-infrastructure-workforce">classifies as essential workers</a> – people who remain on the job even where others have been told to stay home.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/OPLRS9y4wTw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Safe use of pesticides and agricultural chemicals requires knowing how to use, handle and store them, minimize exposure and handle accidents.</span></figcaption>
</figure>
<h2>Pesticides used in US agriculture can impact respiratory health</h2>
<p>Hundreds of thousands of farmworkers in the United States <a href="https://www.cdc.gov/niosh/topics/aginjury/fss/pdfs/FS-18-508.pdf">routinely encounter pesticides on the job</a> And some of the most widely used pesticides in the U.S. pose <a href="https://www.sciencebase.gov/catalog/item/5d88c231e4b0c4f70d0ab2c6">serious health risks</a>, ranging from causing occupational asthma and respiratory irritation to death.</p>
<p>Epidemiological studies, including a long-term study of over 80,000 licensed pesticides applicators conducted by the National Institutes of Health, have found <a href="https://aghealth.nih.gov/about/index.html">links between pesticides and respiratory problems</a>, ranging from acute symptoms such as dry throat, difficulty breathing, chest pain, coughing and wheezing to chronic conditions like decreased lung function, occupational asthma, chronic obstructive pulmonary disease and lung cancer. </p>
<p>Another study by the National Institute for Occupational Safety and Health found that farmworkers had <a href="https://www.cdc.gov/niosh/docs/2007-106/pdfs/2007-106.pdf">significantly elevated mortality</a> for a number of respiratory conditions, including hypersensitivity pneumonitis (also known as “farmer’s lung”), asthma, bronchitis and pneumonia.</p>
<p>Masks can be vital to minimizing the risk. The current shortage of masks comes on top of other risks related to the current health emergency. For example, farm workers often have preexisting conditions, such as those affecting respiratory health, that are <a href="https://www.kff.org/wp-content/uploads/2013/01/migrant-and-seasonal-farmworkers-health-insurance-coverage-and-access-to-care-report.pdf">risk factors for coronavirus</a>. Many live and work in crowded conditions, and have <a href="https://theconversation.com/how-coronavirus-threatens-the-seasonal-farmworkers-at-the-heart-of-the-american-food-supply-135252">difficulty accessing medical care</a>.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/B-RKnYRguXE/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Masks protect farm workers too</h2>
<p>Many farmers and farm workers, especially those who work with pesticides, carry N95 masks. These devices are made of non-woven polypropylene fiber and meet strict government standards for filtering out particles and droplets as small as <a href="https://www.honeywell.com/en-us/newsroom/news/2020/03/n95-masks-explained">0.3 microns, or three one-thousandths of a millimeter</a>. These are often part of a broader PPE kit that can include respiratory protection, gloves, headgear and body, foot and eye protection. </p>
<p>Under U.S. law, employers <a href="https://www.ecfr.gov/cgi-bin/text-idx?SID=586a6ff505fc7d153792f0a56635f0d3&mc=true&node=pt40.26.170&rgn=div5#se40.26.170_1240">must provide appropriate PPE</a> to workers who handle pesticides. The kind of protective equipment needed is determined by a pesticide product’s level of toxicity for five types of acute exposure – oral, dermal, inhalation, eye irritation and skin irritation – as well as whether it is a gas, solid or liquid, and whether the work is being done outdoors or in an enclosed space.</p>
<p>Anyone who handles or assists with the application of pesticides is required to use filtering masks as good as N95s or better when they work with products which are <a href="https://www.epa.gov/sites/production/files/2016-02/documents/chap-10-feb-2016.pdf">lethal or toxic if inhaled</a>, or if risk assessments identify other issues that need to be addressed. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/bo-PEzHE7iw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Proper use of an N95 mask.</span></figcaption>
</figure>
<h2>Reducing risks by managing pests differently</h2>
<p>As the U.S. growing season gets underway, early reports indicate that most farmers <a href="https://news.bloombergenvironment.com/environment-and-energy/farms-could-see-shortage-of-protective-gear-amid-covid-19-needs">have the PPE they need for now.</a> But each N95 mask <a href="https://covid19.ces.ncsu.edu/wp-content/uploads/2020/03/PPE-Guidance-Final-English-Revised.pdf?fwd=no">should only be used for eight hours before being discarded</a>, so with a shortage of masks that is unlikely to abate soon, farmworkers are likely to be caught short. So far, local agricultural agencies have only provided <a href="https://covid19.ces.ncsu.edu/2020/04/personal-protective-equipment-ppe-guidance-for-farms/">limited guidance</a> on how to address the shortage.</p>
<p>So what should farmers and farm workers do? Specific actions will depend on the crop and the pesticide product, but here are some general recommendations.</p>
<p>First, when labels require the use of masks, farmers and farm workers should not work without them. This is unsafe and often illegal. Some hazardous pesticides are only allowed in the market because it is assumed that the use of PPE will <a href="https://doi.org/10.1016/j.ssci.2019.104527">considerably limit exposure</a>.</p>
<p>Nor should pesticide handlers use improvised masks. Bandannas and other kinds of ordinary cloth worn over the nose and mouth do not filter out harmful pesticide particles and droplets, and can even act as reservoirs for pesticide residues.</p>
<p>Instead, I believe farmers should consider reducing risks through adjusting their pest management practices. This is already a recommended best practice: The International Labour Organization’s <a href="https://www.ilo.org/global/topics/safety-and-health-at-work/normative-instruments/code-of-practice/WCMS_160706/lang--en/index.htm">Code of Practice on Safety and Health in Agriculture</a> states that the first line of defense against health effects caused by pesticides should be eliminating or reducing exposure to the hazard, and that PPE should only be used as a last resort. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1232026936378974208"}"></div></p>
<p>The U.S. Occupational Safety and Health Administration also advises that respiratory hazards should be addressed through a “<a href="https://www.cdc.gov/coronavirus/2019-ncov/hcp/respirators-strategy/index.html">hierarchy of controls</a>.” </p>
<p>These reductions can be achieved in a number of ways. They include <a href="https://ipminstitute.org/what-is-integrated-pest-management/">integrated pest management</a>, an approach that finely tunes pesticide application and emphasizes least-risk options; engineering controls that limit contact with pesticides; and replacing highly hazardous pesticides with less hazardous control measures. </p>
<p>Potential substitutes that are generally considered to be <a href="https://www.epa.gov/ingredients-used-pesticide-products/what-are-biopesticides">lower-risk pest management options</a> include microbials (pesticides with a microorganism as the active ingredient), pheromones and beneficial insects. Used together with good crop management, these products can help keep pest levels under control and reduce the need for other pesticides. </p>
<p>But even some of these options pose risks that require use of masks. For instance, repeated exposure to the proteins in some popular microbials can cause allergic sensitization and even lung inflammation. </p>
<h2>An opportunity in a crisis</h2>
<p>Millions of workers in many fields depend on N95 masks and other PPE for safety and health, including farmers and farm workers who have the vital role of feeding the world. Ramping up PPE production may help alleviate the current shortage, but I believe researchers and governments should also try to identify and promote suitable alternatives to pesticides that require such PPE in the first place.</p>
<p>[<em>You need to understand the coronavirus pandemic, and we can help.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=upper-coronavirus-help">Read The Conversation’s newsletter</a>.]</p><img src="https://counter.theconversation.com/content/134976/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr Melanie Bateman is employed by CABI,an international, inter-governmental, not-for-profit organization that receives funding from governments, foundations and the private sector to solve problems in agriculture and the environment. </span></em></p>
One way that farms can handle shortages of protective gear for workers is by switching to less-toxic pest control methods.
Melanie Bateman, Lecturer in Integrated Crop Management, University of Neuchâtel
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/123237
2019-09-25T14:05:05Z
2019-09-25T14:05:05Z
Insects might soon be trained to protect our crops
<figure><img src="https://images.theconversation.com/files/293790/original/file-20190924-54782-i1zlhi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/aphid-close-on-green-leaf-crop-1395578486?src=TWc7y69bRI_yk54yPKYhKA-1-6">Vera Larina/Shutterstock.com</a></span></figcaption></figure><p>One of the biggest contemporary challenges for humanity is to safeguard food security for current and future generations. A growing demand and a steady increase of the world population – nearly <a href="https://www.un.org/development/desa/en/news/population/world-population-prospects-2017.html">10 billion</a> people are expected to inhabit Earth by 2050 – requires that food production per area of cultivated land will have to increase drastically. Expanding into land that is currently uncultivated is not feasible, especially considering the pressures of climate change.</p>
<p>One way to achieve higher yields will be reducing crop losses caused by pests, including insects. For instance, in cereal crops such as rice and maize, which are staple foods for a large part of the world’s population, insects result in up to <a href="https://science.sciencemag.org/content/361/6405/916">15% losses</a>. </p>
<p>Spraying chemical insecticides remains the main approach to combating insect attacks in many crops. But their future use is under scrutiny because of many concerns, not least their effects on <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4947579/">human health</a>. Their use also represents a large <a href="https://www.sciencedirect.com/science/article/pii/S0921800901002385">economic burden</a> on growers, especially those in developing countries. And in any case, it is feared that insects will soon <a href="https://www.sciencedirect.com/science/article/pii/S0965174814000794?via%3Dihub">develop resistance</a> to insecticides.</p>
<p>Curtailing their use would also be good for the planet, as insecticides are inherently unsustainable: their continuous use has resulted in massive environment pollution, which <a href="https://www.sciencedirect.com/science/article/pii/S0921800901002385">negatively affect</a> other beneficial organisms such as bees, birds, fishes and livestock. This means that there is increasing <a href="https://www.sciencedirect.com/science/article/pii/S0950329317300198">consumer demand</a> for residue-free food. Linked to this, the availability of insecticides for insect management is declining globally due to considerable changes in <a href="https://academic.oup.com/jxb/article/62/10/3251/484038">their legislation</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/293806/original/file-20190924-51414-1igmfn8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293806/original/file-20190924-51414-1igmfn8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293806/original/file-20190924-51414-1igmfn8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293806/original/file-20190924-51414-1igmfn8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293806/original/file-20190924-51414-1igmfn8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293806/original/file-20190924-51414-1igmfn8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293806/original/file-20190924-51414-1igmfn8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Pesticides are not a sustainable solution.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/tractor-spraying-field-corn-419658139?src=pICnnT_ToCRkmmwZqhZJCw-1-67">Pajtica/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>So there is an urgent need to find alternatives – preferably environmentally friendly strategies for protecting crops against insects.</p>
<h2>Controlling bad insects with good ones</h2>
<p>Biological control, in which insect populations are reduced by using other insects (their natural enemies) is <a href="https://link.springer.com/article/10.1007/s10526-017-9801-4">generally accepted</a> as a sustainable and ecologically sound approach to reduce crop losses by insects.</p>
<p>These natural enemies are often highly specialised and only attack a certain number of closely related insect pests, reducing the likelihood of unforeseen knock-on effects on the rest of the local ecosystem that are commonly caused by insecticides. Natural enemies can also be introduced to control new invading insect pests. For example, European natural enemies were introduced in North America to control a new infestation of <a href="https://www.sciencedirect.com/science/article/pii/B9780124171565000010">bark beetles</a>, which carry and spread Dutch elm disease.</p>
<p>Natural enemies of insect pests include predators, pathogens (micro-organisms that include bacteria, fungi, and viruses), and <a href="https://www.britannica.com/science/parasitoid">parasitoids</a> (mostly wasps or flies which lay their eggs on or in other insect, eventually killing them as the larvae grow). Parasitoids are the most effective of these three types because their numbers increase much faster than those of the predators. In addition, they are highly specialised, as they are only able to lay their eggs in a specific species and therefore have minimal effects on the rest of the ecosystem.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/293807/original/file-20190924-51463-puogu8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293807/original/file-20190924-51463-puogu8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=465&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293807/original/file-20190924-51463-puogu8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=465&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293807/original/file-20190924-51463-puogu8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=465&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293807/original/file-20190924-51463-puogu8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=585&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293807/original/file-20190924-51463-puogu8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=585&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293807/original/file-20190924-51463-puogu8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=585&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Parasitoid female and aphid nymph.</span>
<span class="attribution"><span class="source">© Tim Goelen</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Parasitoids are very diverse and constitute of a staggering number of insect species (nearly <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev.en.29.010184.000513">14%</a> of all described insects). Many species are currently mass-reared in commercial insectaries to be released in big numbers to obtain immediate control of the pests attacking orchards or greenhouses. But their effectiveness needs to be improved. This not only demands increasing their numbers in the fields, but also enhancing their foraging success.</p>
<h2>The sweet scent of nectar</h2>
<p>While foraging for food or hosts, parasitoids generally depend on visual and olfactory cues. For example, they often locate resources from particular flowers by responding to the scent and colour of flowers. They possess the ability to learn associations between these cues and rewards such as food or host, cleverly using this learned information the next time. This allows them to find their resources faster and therefore increase their foraging success.</p>
<p>Parasitoids forage for carbohydrate-rich food such as floral nectar. Floral nectar is an ideal habitat for diverse microbes such as yeasts, which not only alter its composition of sugars and amino acids, but also produce special scents. These scents produced by nectar yeast are very attractive to parasitoids.</p>
<p>If we want to help out parasitoids in the field, in order to increase their numbers and therefore help them control pests, we need to know more about how the microbial cues produced by nectar yeasts influence learning of floral preferences by parasitoids. This is what we set out to achieve in a <a href="https://www.sciencedirect.com/science/article/pii/S0003347219301447">recent experiment</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/293809/original/file-20190924-51452-q3q22e.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293809/original/file-20190924-51452-q3q22e.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=585&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293809/original/file-20190924-51452-q3q22e.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=585&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293809/original/file-20190924-51452-q3q22e.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=585&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293809/original/file-20190924-51452-q3q22e.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=735&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293809/original/file-20190924-51452-q3q22e.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=735&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293809/original/file-20190924-51452-q3q22e.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=735&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mummified aphids – with parasitoid pupae.</span>
<span class="attribution"><span class="source">© Tim Goelen</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We wanted to find out whether frequent visits by parasitoids to flowers predisposes them to learn and remember the smell of tasty, energy-rich nectar produced by yeast. To this end, we investigated the learning ability and memory retention of an aphid parasitoid (aphids cause tremendous yield losses in crops worldwide) when exposed to volatile mixtures emitted from nectars. These nectars were artificially synthesised and fermented by various nectar yeasts, mimicking natural nectars.</p>
<p>We showed that naïve aphid parasitoids (those inexperienced to smell and food) had an innate (inborn) preference for nectar colonised by specific nectar yeasts. When parasitoids were trained, by allowing them to feed on a filter paper saturated with yeast-fermented nectar for two minutes, something that was repeated three times, they were very strongly attracted to these and other yeast-fermented nectars for the next 24 hours. This shows that when parasitoids are trained they are able to forage for nectar much faster in the field.</p>
<p>Our <a href="https://www.sciencedirect.com/science/article/pii/S0003347219301447">findings</a> may have practical implications in enhancing the effectiveness of parasitoids to be used in biological control programs against aphids. They promote the possibility that parasitoids, owing to such high learning ability, could be mass trained before field release to induce a specific response to yeast-fermented sugar solutions and improve their performance in finding food and aphid hosts.</p>
<p>Such solutions could be offered in feeding stations to feed and retain the parasitoid populations in the field where natural food sources are limited. This would in turn improve the foraging efficiency of trained parasitoids and increase their overall efficacy in suppressing aphid populations.</p><img src="https://counter.theconversation.com/content/123237/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Research in the Laboratory of Bart Lievens is funded by FWO and VLAIO. </span></em></p><p class="fine-print"><em><span>Islam Sobhy does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Certain wasps and flies which lay their eggs in specific species such as aphids could be a sustainable form of pest control.
Islam Sobhy, Research Associate in Chemical Ecology, Keele University
Bart Lievens, Research Group Leader, Laboratory for Process Microbial Ecology and Bioinspirational Management, KU Leuven
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/118669
2019-09-03T23:09:57Z
2019-09-03T23:09:57Z
3 ways insecticides can be counterproductive in agriculture
<figure><img src="https://images.theconversation.com/files/290201/original/file-20190829-106517-191ipmu.jpg?ixlib=rb-1.1.0&rect=182%2C85%2C3606%2C2053&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some insecticides make pests stronger or put plants at greater risk of attack. </span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Pesticides are not new and are definitely not a human invention. Plants and other microorganisms have used chemicals to defend themselves from other organisms for hundred thousands of years. </p>
<p>Take, for example, walnut trees. Their <a href="http://www.omafra.gov.on.ca/english/crops/facts/info_walnut_toxicity.htm">roots produce a chemical called juglone</a> that is secreted into the soil and inhibits nearby plant growth. This ensures the walnut tree has all the nearby nutrients and water for itself.</p>
<p>Plants also produce insecticides. Nicotine is the most famous example, produced by plants in the solanaceae family, including tomatoes, potatoes and, of course, tobacco. Many plant-eating insects avoid tobacco plants because nicotine is a <a href="https://doi.org/10.1002/ece3.4750">powerful neurotoxin that can kill them</a>.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/289954/original/file-20190828-184217-100pb1c.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/289954/original/file-20190828-184217-100pb1c.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=854&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289954/original/file-20190828-184217-100pb1c.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=854&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289954/original/file-20190828-184217-100pb1c.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=854&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289954/original/file-20190828-184217-100pb1c.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1073&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289954/original/file-20190828-184217-100pb1c.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1073&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289954/original/file-20190828-184217-100pb1c.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1073&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Black walnut, pecan, hickory and other trees in the walnut family produce a chemical called juglone that may be toxic to nearby plants.</span>
<span class="attribution"><span class="source">Wikimedia</span></span>
</figcaption>
</figure>
<p>Humans have replicated this natural chemical warfare to produce pesticides that have become essential for agriculture. But insecticide use also raises concerns about their impact on non-target species such as bees, or their indirect effect on birds, which eat a lot of insects.</p>
<p>Scientists who study insects and how they adapt to pesticides are discovering that some insecticides can make pests stronger or that the plant itself might even become under greater attack from other pests. Finding solutions is important both for preserving biodiversity and agriculture.</p>
<p>When a farmer uses insecticides, they are aware of beneficial effects on their fields but they need also be aware of the potential negative impacts. </p>
<h2>What doesn’t kill you makes you stronger</h2>
<p>A pesticide can provoke a resurgence of the target pest in the days, weeks or months that follow its application. Insecticides must be applied at lethal concentrations and sometimes several times during the pest’s lifecycle to be fully effective. </p>
<p>At sub-lethal concentrations, a pesticide can, in fact, <a href="https://www.doi.org/10.1021/bk-2017-1249.ch008">increase the fecundity or the longevity of some pests</a>. For example, when imidacloprid (an insect neurotoxin from the neonicotinoid family) is applied at sub-lethal concentrations, it can <a href="https://doi.org/10.1007/s10340-015-0716-5">double the reproduction rate of the green peach aphid</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/287895/original/file-20190813-9429-10kfdtd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/287895/original/file-20190813-9429-10kfdtd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/287895/original/file-20190813-9429-10kfdtd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=731&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287895/original/file-20190813-9429-10kfdtd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=731&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287895/original/file-20190813-9429-10kfdtd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=731&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287895/original/file-20190813-9429-10kfdtd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=919&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287895/original/file-20190813-9429-10kfdtd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=919&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287895/original/file-20190813-9429-10kfdtd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=919&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The green peach aphid.</span>
<span class="attribution"><a class="source" href="http://www.ars.usda.gov/is/graphics/photos/sep01/k9602-1.htm">Scott Bauer, USDA</a></span>
</figcaption>
</figure>
<p>Even worse, a <a href="https://doi.org/10.1016/j.baae.2018.05.001">sub-lethal pesticide application can rapidly lead to the emergence of insecticide resistance</a>. Pesticide resistance makes these chemicals useless or even detrimental. This is the case for the insecticide-resistant strain of maize weevil, which <a href="https://doi.org/10.1111/j.1439-0418.2009.01462.x">increased its population 5.4-fold when treated by a pyrethroid insecticide called deltamethrin</a>. </p>
<h2>Outbreaks on repeat</h2>
<p>Insecticides can be selective — targeting a particular insect — or act on a range of pests (broad spectrum). Broad-spectrum insecticides are widely used, but can have detrimental adverse effects such as disrupting a pest’s natural enemies. </p>
<p>In these cases, a few weeks after the pesticide is applied, the same pest will <a href="https://doi.org/10.1007/978-1-4020-6061-8_2">re-appear in the field (primary pest resurgence) or an outbreak of another pest will occur (secondary pest resurgence)</a>. These phenomena have been identified on many crops, including <a href="http://dx.doi.org/10.1007/s10340-011-0374-1">soybean</a>, <a href="https://doi.org/10.1111/agec.12259">potato</a> and <a href="https://doi.org/10.1002/9781119255574.ch4">more</a>, but they’re difficult to study because there are so many different factors involved. </p>
<p>Some researchers have estimated that an early season pesticide treatment on cotton for lygus bugs can add <a href="https://doi.org/10.1890/11-0118.1">US$6 per acre</a> for a subsequent late-season pesticide application because the pest’s natural enemies are depleted. </p>
<h2>The sensitive plant</h2>
<p>Some pesticide manufacturers now coat the plant seeds with pesticide, so that the plants take up the pesticide in their organs and become toxic to agricultural pests. This has become a very popular way to protect annuals such as wheat, soybean or corn. </p>
<p>But when a plant becomes resistant to some pests, it can also become more sensitive to others. The best documented example is the use of neonicotinoids on <a href="https://doi.org/10.1603/ec10125">cotton</a>, <a href="https://doi.org/10.1371/journal.pone.0062620">corn and tomato</a>, and the rise of two-spotted spider mite outbreaks. Spider mites are not susceptible to neonicotinoids and thrive on these crops much more compared to the untreated ones. </p>
<p>Without a doubt, <a href="https://doi.org/10.1016/j.cropro.2007.03.022">pesticides contribute positively to high and stable crop production in our current agricultural model and therefore in our lives</a>. On the other hand, there are non-chemical options that can be used as alternatives or in addition to pesticides. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/microbial-aromas-might-save-crops-from-drought-103960">Microbial aromas might save crops from drought</a>
</strong>
</em>
</p>
<hr>
<h2>Insecticide alternatives</h2>
<p>There are opportunities to reduce pesticide use, and scientists, like myself, work on many sustainable alternatives. A recent study highlighted that <a href="https://doi.org/10.1016/j.envint.2019.04.045">78 per cent</a> of the neonicotinoids used in agriculture could be replaced by non-chemical pest management. Among many others, an amazing <a href="http://www.the-jena-experiment.de/Home.html">initiative in Germany</a> called Jena is gathering researchers to see if bringing more plant diversity to the field increases resilience when compared to our mono-cultural agricultural systems. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/j3SvG2nBCTM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Jena Experiment.</span></figcaption>
</figure>
<p>Several new technologies are under development that could help reduce pesticide use. For example, cameras can detect the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5855517/">volatile chemicals released</a> by plants during a pest outbreak. These warning signals can help farmers detect pests sooner and lead to a better, more efficient treatment. </p>
<p>Biotechnology can also help. Genetically modified crops have <a href="https://doi.org/10.1080/09644016.2011.551023">not been broadly accepted by the public</a>, but new techniques such as CRISPR-Cas9 — a precise genetic tool able to change small parts of the genome — can, if used wisely, be <a href="https://dx.doi.org/10.3390%2Finsects7030046">invaluable to a more sustainable, less pesticide-dependent, agriculture</a>. For example, a plant can be designed to <a href="https://doi.org/10.1016/j.tplants.2012.03.012">attract natural enemies by emitting volatile compounds, therefore protecting against some pests</a>. </p>
<p>Under the current agricultural model, pesticides are almost essential to provide sufficient food to the global population. But there are alternatives, and buying food from farmers that have stopped or limited pesticide use is one way to support an agricultural transition away from pesticides. </p>
<p>[ <em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/ca/newsletters?utm_source=TCCA&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=youresmart">You can read us daily by subscribing to our newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/118669/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julien Le Roy does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Pesticides have become almost essential for agriculture, but their misuse can have negative effects on crops too.
Julien Le Roy, Postdoctoral associate, Department of Biology, Western University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/119916
2019-07-08T10:27:30Z
2019-07-08T10:27:30Z
Armyworms are devastating Asia’s crops, but we have a plan to save them
<figure><img src="https://images.theconversation.com/files/282872/original/file-20190705-51297-ceimwh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fall-armyworm-spodoptera-frugiperda-smith-1797-480586348?src=IFX1n5GoxJ7-CJJO6VRQSw-1-3&studio=1">Mikhail Kochiev/Shutterstock</a></span></figcaption></figure><p>A very hungry caterpillar is rampaging through crops across the world, leaving a trail of destruction in its wake. The fall armyworm, also known as <em>Spodoptera frugiperda</em> (fruit destroyer), loves to eat maize (corn) but also plagues many other crops vital to human food security, such as rice and sorghum.</p>
<p>This invasive eating machine originated in the Americas, where it was first described <a href="https://www.jstor.org/stable/3495726?seq=1#page_scan_tab_contents">in 1797</a>, but in the last few years it has gone global. It was <a href="https://theconversation.com/armyworms-are-wreaking-havoc-in-southern-africa-why-its-a-big-deal-72822">reported in Africa</a> in 2016 and has now reached China, spreading across two continents, west to east, in just three years. Entry of the pest into this part of Asia matters because so many people live there and in nearby regions, and there is already huge pressure on the area’s food production systems.</p>
<p>But there is hope. My colleagues and I are researching ways to stop the pest that don’t rely on damaging pesticides and could be adopted around the world.</p>
<p>How the fall armyworm crossed the Atlantic from its native range in tropical and subtropical regions of the Americas is unknown. Perhaps it was through long-distance migration of moths, possibly blown by winds, that then laid eggs in Africa. Or perhaps it was through trade of contaminated produce already containing eggs and hungry caterpillars.</p>
<p>Yet while the means of entry is unknown, the outcome is clear. Crops – and livelihoods – are being ruined. The armyworm can destroy as much as 50% of a producer’s crop, and the effect on small farmers growing crops to feed their families is terrible.</p>
<p>What’s more, because adult moths can travel hundreds of kilometres, the pest rapidly spread across most of <a href="https://theconversation.com/armyworms-are-wreaking-havoc-in-southern-africa-why-its-a-big-deal-72822">sub-Saharan Africa</a> wreaking havoc as it went. It’s estimated that crop losses in 12 African countries could be as high as <a href="https://www.cabi.org/news-and-media/2017/new-report-reveals-cost-of-fall-armyworm-to-farmers-in-africa-provides-recommendations-for-control/">US$6.1 billion a year</a>.</p>
<p>But it didn’t stop there. In July 2018, it was found in <a href="https://www.thehindu.com/news/national/karnataka/alarm-as-deadly-maize-pest-seen-in-karnataka/article24636285.ece">Karnataka state in India</a>, the first reported infestation in Asia. By December 2018 it had <a href="https://www.ippc.int/en/countries/thailand/pestreports/2018/12/first-detection-of-fall-army-worm-on-the-border-of-thailand/">spread to Thailand</a>, and it’s still going, now reported in <a href="https://www.ft.com/content/8688327c-97c4-11e9-8cfb-30c211dcd229">over half the provinces of China</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/282873/original/file-20190705-51288-1rowws8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282873/original/file-20190705-51288-1rowws8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282873/original/file-20190705-51288-1rowws8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282873/original/file-20190705-51288-1rowws8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282873/original/file-20190705-51288-1rowws8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282873/original/file-20190705-51288-1rowws8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282873/original/file-20190705-51288-1rowws8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Fall armyworms are known for their resistance to pesticides.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/asian-farmer-peasantry-spraying-pesticides-rice-1194794023?src=xd8B7ha0w4Y91ujdtHR6nw-3-33&studio=1">Tong Stocker/Shutterstock</a></span>
</figcaption>
</figure>
<p>It is quite remarkable that fall armyworm has managed to cross two continents in such a short space of time. There are vast swathes of crops now vulnerable to the pest and it has now spread too much to be eradicated so its populations have to be managed.</p>
<p>The immediate reaction in many places has been to use pesticides, but the fall armyworm is well known for its <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0062268">ability to evolve resistance</a> to these. And more powerful, general insecticides could kill helpful insects that are natural enemies of the pest. However, using some more natural defences may actually be a feasible strategy, as well as more environmentally friendly one.</p>
<h2>Four-part solution</h2>
<p>In collaborative research with the International Centre of Insect Physiology and Ecology in Kenya, my colleagues and I are developing four ways to increase resilience to the pest. First, we are assessing the natural resistance levels of crops to determine which varieties are more robust against attack by the pest. Early results show that damage can be partly reduced this way.</p>
<p>Second, we are attempting to drive pests away from the main crop by interspersing it with a crop that they dislike because it releases repellent odours associated with an already damaged plant. And third, we’re planting what are known as attractive trap plants to lure the worm to alternative locations. This technique is known as a “push-pull” companion cropping system and is currently used successfully against stem-borer pests. Early results show <a href="http://www.icipe.org/news/icipe-push-pull-technology-halts-fall-armyworm-rampage">substantial reductions</a> in fall armyworm infestation in push-pull system fields.</p>
<p>Fourth, we are attempting to attract local predators of the pest, such as parasitic wasps that will kill it by laying their own eggs inside the caterpillar. To do this, we are using attractive companion crops and others that release a <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1461-0248.2011.01674.x">cry for help signal</a> - an odour released by the plant when it is attacked to summon bodyguard insects.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-trees-communicate-via-a-wood-wide-web-65368">How trees communicate via a Wood Wide Web</a>
</strong>
</em>
</p>
<hr>
<p>Our research requires a detailed understanding of the predators and parasites that are the key natural enemies of the invasive fall armyworm. So a major part of our project is trying to understand the current pest and predator relationship where the crops are being grown. We are working closely with local farmers to develop the system. </p>
<p>Our hope is that this strategy of combining attempts to resist, expel, trap and kill the fall armyworm should provide a novel cropping system that can withstand attack. While our project is based in Kenya, we hope that similar approaches can be used in Asia and across the world.</p><img src="https://counter.theconversation.com/content/119916/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Toby Bruce receives funding from the BBSRC (Biotechnology and Biological Sciences Research Council).</span></em></p>
The rice-eating fall armyworm has spread across Asia in a year and is now found in half the provinces of China.
Toby Bruce, Professor of Insect Chemical Ecology, Keele University
Licensed as Creative Commons – attribution, no derivatives.